CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL 

 LABORATORY, HARVARD UNIVERSITY. 



WATER, IN THE LIQUID AND FIVE SOLID FORMS, 



UNDER PRESSURE. 



By p. W. Bridgman. 



Presented by G. W. Pierce, October, 11, 1911. Received October 6, 1911. 



Introduction. 



The purpose of this paper is the same as that of the immediately 

 preceding paper on mercury, — to indicate the nature of the funda- 

 mental facts which must be taken account of in any theory of liquids 

 valid for high pressures, and to find something about the nature of the 

 equilibrium between crystal and liquid. Both of these subjects are as 

 yet practically untouched. AU present theories of liquids are incom- 

 petent to explain known facts, and as for the theory of the equilibrium 

 liquid-solid, even the fundamental facts are unknown. It seems, more- 

 over, that these two subjects will find their best development side by 

 side ; one involves the other. Thus, any normal liquid may be made 

 to crystallize by the application of high pressure. The internal forces 

 producing crystallization must be present to some extent continuously 

 in the liquid, modifying its behavior more and more as the crystalliza- 

 tion point is approached. Yet no present theory of liquids takes ac- 

 count of these vector forces in the liquid which ultimately produce 

 crystallization, but supposes instead that the force between molecules is 

 uniform in every direction. 



To be of significance the experimental study must be made over a 

 comparatively wide pressure range, the order of the pressures being 

 many fold greater than the pressures involved in the corresponding 

 study of the liquid- vapor change. The results of this paper reach to 

 20,500 kgm./cm.^, whereas the highest previous pressure under which 

 water has been studied was only 3500 kgm. 



As compared with mercury, the results for water are much more 

 varied and richer in suggestion. It is well known that under ordinary 

 conditions water is abnormal in many respects. The effect of high 



